1. Field of the Invention
The present invention relates to a molding machine for molding a gas hydrate by compression molding, and more specifically to a molding apparatus suitable for making pellets by compression molding of a gas hydrate in a high-pressure gas atmosphere.
2. Description of Related Art Including Information Disclosed Under 37 CFR §§1.97 and 1.98
Generally molding pellets by compressing powder adopts a molding apparatus having a pair of forming rolls having molding concavities on the surface thereof. As shown in FIG. 6, for example, the molding apparatus has a casing 4 which contains two forming rolls 6a and 6b being arranged closely to each other, a feed opening 2 for the powder a at the upper part of the casing 4, and a discharge opening 3 for the pellets, which were formed by compression molding, at the lower part of the casing 4.
In the molding apparatus 1 having the above structure, the powder a is supplied to the forming rolls 6a and 6b by a screw transfer unit 16. The powder a is pressed and compacted in the molding concavities formed on the surface of the respective rolls 6a and 6b to become pellets P, which pellets P are then discharged from the discharge opening 3.
The applicant of the present invention has already proposed a method for increasing the filling rate of gas hydrate, for improving the stability and safety during transportation and storage of the gas hydrate, or for improving the handling of the gas hydrate loading/unloading through the procedure that a raw material gas, containing methane as a principal component, such as natural gas, is brought into gas-liquid contact with water, under a specified pressure and temperature condition (for example, 5.4 MPa and 4° C.), to thereby form the gas hydrate, which gas hydrate is then molded into pellets through the compression molding by a pair of rotary rolls in said pressure atmosphere (for example, Patent Document 1).    Patent Document 1: Japanese Patent Application Kokai Publication No. 2002-220353